1. Field of the Invention
This invention relates to an optical disk device adapted to carry out recording or reproduction of an information signal through a laser beam while rotating an optical disk, and more particularly to an optical disk device to which a measure for heat generated therein is taken.
2. Description of the Related Art
In memories or storages for a computer, a standard dimension so called a form factor is prescribed. Optical disk devices or units which are one of such memories or storages are commercialized in such a manner that they satisfy the requirement of the standard dimension. Explanation will be given by taking a more actual example of the standard dimension. For example, the so-called disk devices of the full height of 5.25 inches have a height (H.sub.F) of 82.5 mm, a width (W.sub.F) of 146.0 mm, and a depth (D.sub.F) of 203.2 mm (height (H.sub.F) is 3.25 inches, width (W.sub.F) is 5.75 inches, and depth (D.sub.F) is 8.00 inches in terms of the inch size). Further, disk devices of the half height of 3.5 inches have a height (H.sub.H) of 41.3 mm, a width (W.sub.H) of 101.6 mm, and a depth (D.sub.H) of 146.0 mm (height (H.sub.H) is 1.625 inches, width (W.sub.H) is 4.00 inches, and depth (D.sub.H) is 5.75 inches in terms of the inch size).
Meanwhile, it is well known in such optical disk devices that the weight of the pickup system, i.e., its movable part is large, and that heat resulting from light emitting driving of a laser beam or irradiation of a laser beam, or a quantity of heat in driving a linear voice coil motor is produced to considerably much degree. While ICS or electronic parts which are circuit components or elements constituting a light emitting control unit for a laser beam or an optical pickup and positioning control unit of the device itself are not affected by such heat, if the ambient internal temperature within the device is above 55.degree. C. which is an upper limit specification of the temperature guarantee standard requirement as a recording medium, e.g., pits serving to record information signals into the recording medium are affected by heat, giving rises to inconveniences such that, e.g., tracking cannot sufficiently carried out. For this reason, there is the possibility that the optical disk device may fail to stably write information signals onto the recording medium. In order to allow the optical disk device to write information signals thereonto in a stable state at all times, the optical disk device is adapted so that the operation of the circuit therein is caused to be stopped at the time point when the internal temperature is above the aforementioned temperature.
Accordingly, in a computer control system adapted so that such optical disk device is attached therein, such optical disk device is arranged at the position in the vicinity of an air-cooling fan for cooling provided in an equipment such as the computer, etc., thus to cool the heat producing portions within the optical disk device. For this reason, it was necessary to allow flow of air within the computer control system dependent upon the position of the air-cooling fan for cooling to be securely in contact with the heat producing portions of the optical disk device, thus to cool those portions. As stated above, the arrangement position of the optical disk device is dependent upon the position of the air-cooling fan for cooling arranged within the computer control system. Namely, the degree of freedom of attachment position of the optical disk device in including this device within the computer control system becomes small. As a result, under present circumstances, it is difficult to manufacture a computer control system including such optical disk device therein.
In future, it is anticipated to realize products in which a small optical disk device having a large memory capacity is included in a computer control system or equipment, although such products have problems as described above. In addition, under the circumstances where there is a tendency that optical disk devices are being miniaturized, a measure for heat as mentioned above particularly in an optical magnetic disk device of 3.5 inches, for example, is very important mater.